Magnesium base alloy



Patented June 16, 1942 MAGNESIUM BASE 'ALLOY John C. McDonald, Midland,Mich., assignor to The Dow Chemical Company, Midland, Micln, acorporation of Michigan No Drawing.

Application December 23, 1940,

Serial No. 371,379

2 Claims.

The invention relates to magnesium base alloys and more particularlyconcerns an alloy of this nature having a high degree of formabilityas-.- sociated with other desirable physical properties, such asexcellent tensile and yield strengths Magnesium base alloys are beingwidely used in the structural arts where a lightweight metal is highlydesirable, such as for use in making castings, forgings, and the like.However, the use of these alloys in the rolled form to make sheet metalarticles requiring forming operations, such as bending and drawing, hasnot progressed as rapidly due to the fact that, in

general, alloys having good formability or due-- -tility permittingrelatively sharp bends to be made without the article developingexternal cracks, usually have inferior characteristics as regards theirtensile and yield strengths.

sharply bent, drawn or otherwise shaped, while having good tensile andyield strengths.

Other objects and advantages-will be apparent as the description of theinvention proceeds.

My invention resides in the discovery that a magnesium base alloycontaining from 0.01 to 1 per cent of calcium, from 0.01 to 1per cent ofcerium, and from 1 to 15 per cent of thallium Table Nominal compositionin percent (mag- Annealed nesium=remainder) Per cent Yield Tensile Ce CaTl elongation strength in strength in in 2 inches lbs/sq. in. lbs/sq.in.

possesses the aforementioned desirable properties. The term magnesiumused herein and in the appended claims is intended to include magnesiumcontaining the ordinary impurities that are found in the commerciallypure metal, such as traces of iron, copper, nickel, and silicon. Whilethe properties of improved ductility or formability associated with hightensile and yield strengths are manifest over the entire range ofcomposition indicated, a particularly desirable composition, because ofits combination of properties is one containing 0.2 per cent calcium,0.2 per cent of cerium, and 5 per cent of thallium. I

The following table, listing some of the properties of rolled sheetmadeirom my new alloy and comparing these properties with those of somerelated alloys, illustrates the improvement in formability, yield andtensile strengths shown by the new alloy.

In the table, the per cent elongation is to be regarded as a measure ofthe ductility or formability of the alloys.

The properties set forth above under the term annealed were obtained byfirst rolling the alloys at atemperature of 550 F. and thereafterannealing them at various temperatures through a range of from 400 to800 F. The properties selected for the table were those of the annealedspecimens which exhibited the maximum elongation.

A comparison of the properties listed in the 0 above table shows thatthe new alloy possesses superior formability characteristics coupledwith improved-yield and tensile strengths. The improvement noted in thecomposition listed is exhibited throughout the percentage range ofalloying ingredients indicated.

While the new alloy is most useful in wrought form, such as sheets, dueto its formability v characteristics, it may also be used for makingcastings, extruded forms, and the like.

The new alloy may be compounded by any of the methods usually employedfor melting and alloying metals with magnesium such as by adding thealloying ingredient singly or jointly to a bath of molten magnesiumwhich ispreferably protected from oxidation by suitable flux. The fluxshould be substantially free from magnesium chloride, if the calciumcontent of the alloy is above 0.3 per cent. In those instances where thealloy is to be compounded containing less than 0.3 per cent of calcium,magnesium chloride may be present in the flux, but in this case it ispreferable to add'the calcium last without too much stirring oragitation in order to pre- It is to be understood that the invention isnot limited to the specific composition herein described, but may takeother forms without departing from the scope of the invention.

I claim:

1. A magnesium base alloy containing 0.01 to 1 per cent of calcium, from0.01 to 1 per cent of cerium, and from 1 to 15 per cent of thallium, thebalance being magnesium.

2. A magnesium base alloy containing 0.2 per cent of calcium,0.2 percent of cerium, and 5 per cent of thallium, the balance being magnesium.

JOHN C. MCDONALD.

